Method for processing metal-cast article

ABSTRACT

A method for processing a metal-cast article according to an aspect of the present invention includes a correcting step of starting to pressurize the metal-cast article by a press machine ( 10, 20 ) before a temperature of the metal-cast article  40  decreases to 200° C. or lower after casting is finished. Distortion can be accurately removed in a correction of a metal-cast article. Further, since there is no need to heat the metal-cast article again for the correction, the productivity and energy efficiency can be improved.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2015-082589, filed on Apr. 14, 2015, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for processing a metal-castarticle, and in particular to a method for processing a metal-castarticle including a correcting step.

2. Description of Related Art

For example, in thin-walled metal-cast articles such as metal-castarticles formed by aluminum die casting, distortion tends to occur, forexample, when they are taken out from casting apparatuses. In somecases, a metal-cast article undergoes a press-correction after asolution treatment or the like in order to remove such distortion.

In Japanese Unexamined Patent Application Publication No. 2004-322154, ametal-cast article undergoes a press-correction at a normal temperatureafter an aging process.

SUMMARY OF THE INVENTION

The inventors have found the following problem in the above method forprocessing a metal-cast article.

It is very difficult to accurately remove distortion by a correction ata normal temperature like the one disclosed in Japanese UnexaminedPatent Application Publication No. 2004-322154. Further, a large load isrequired for the correction. Therefore, in some cases, a correction isperformed with heating the metal-cast article again, for example, afterthe solution treatment or the like.

However, such heating for a correction needs to be separately performedfrom the solution treatment and the aging process. Therefore, there hasbeen a problem that the above-described processing method in which aseparate heating process is necessary has poor productivity and poorenergy efficiency.

The present invention has been made in view of the above-describedcircumstances, and an object thereof is to provide a method forprocessing a metal-cast article capable of accurately removingdistortion in a correcting process for the metal-cast article andthereby having excellent productivity and energy efficiency.

A first exemplary aspect of the present invention is

-   -   a method for processing a metal-cast article including a        correcting step of starting to pressurize the metal-cast article        by a press machine before a temperature of the metal-cast        article decreases to 200° C. or lower after casting is finished.

In the method for processing a metal-cast article according to theaspect of the present invention, the correction is performed by startingthe pressurization of the metal-cast article by the press machine beforethe temperature of the metal-cast article decreases to 200° C. or lowerafter the casting is finished. Therefore, the correction is performed ata relatively high temperature, thus making it possible to accuratelyremove distortion even when the load for the correction is small.Further, compared to the case where the correcting process is separatelyperformed after the solution treatment, there is no need to heat themetal-cast article again for the correction. Therefore, the productivityand energy efficiency are excellent.

The method preferably further includes a trimming step of cooling themetal-cast article to a normal temperature while maintaining thepressurized state of the metal-cast article by the press machine, andshearing off an unnecessary part of the metal-cast article. The timerequired for the trimming of the metal-cast article can be reduced andhence the productivity can be further improved.

Further, the press machine preferably includes an upper mold and a lowermold with a refrigerant channel formed therein, and when the metal-castarticle is cooled, a refrigerant is preferably made to flow through therefrigerant channel. The metal-cast article can efficiently be cooledwhile maintaining the metal-cast article in the pressurized state.

Further, when the metal-cast article is cooled, the temperature of themetal-cast article is preferably measured and the flow rate of therefrigerant is preferably adjusted based on the measured temperature.The metal-cast article can be uniformly cooled.

According to the present invention, it is possible to provide a methodfor processing a metal-cast article capable of accurately removingdistortion in a correcting process for the metal-cast article andthereby having excellent productivity and energy efficiency.

The above and other objects, features and advantages of the presentinvention will become more fully understood from the detaileddescription given hereinbelow and the accompanying drawings which aregiven by way of illustration only, and thus are not to be considered aslimiting the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing a method for processing a metal-castarticle according to a first exemplary embodiment;

FIG. 2 is a flowchart showing a method for processing a metal-castarticle according to a comparative example;

FIG. 3 is a schematic temperature chart showing a comparison between themethod for processing a metal-cast article according to the firstexemplary embodiment and that according to the comparative example;

FIG. 4 is a schematic cross section showing a correction apparatus for ametal-cast article according to the first exemplary embodiment;

FIG. 5 is a schematic cross section showing the correction apparatus fora metal-cast article according to the first exemplary embodiment;

FIG. 6 shows a plan view showing an arrangement example of coolantchannels WC and thermocouples TC in an upper mold, and cross sectionstaken along respective cutting lines in the plan view;

FIG. 7 is a flowchart showing a method for controlling a coolingtemperature for a metal-cast article;

FIG. 8 is a flowchart showing a method for processing a metal-castarticle according to a second exemplary embodiment;

FIG. 9 is a schematic temperature chart showing a comparison between themethod for processing a metal-cast article according to the firstexemplary embodiment and that according to the second exemplaryembodiment;

FIG. 10 is a schematic cross section showing a correction apparatus fora metal-cast article according to the second exemplary embodiment;

FIG. 11 is a schematic cross section showing the correction apparatusfor a metal-cast article according to the second exemplary embodiment;and

FIG. 12 is a schematic cross section showing the correction apparatusfor a metal-cast article according to the second exemplary embodiment.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Specific exemplary embodiments to which the present invention is appliedare explained hereinafter in detail with reference to the drawings.However, the present invention is not limited to exemplary embodimentsshown below. Further, the following descriptions and the drawings aresimplified as appropriate for clarifying the explanation.

First Exemplary Embodiment

Firstly, a method for processing a metal-cast article according to afirst exemplary embodiment of the present invention is explained withreference to FIG. 1. FIG. 1 is a flowchart showing a method forprocessing a metal-cast article according to the first exemplaryembodiment. As an example, a metal-cast article formed by aluminum diecasting is explained. As shown in FIG. 1, the method for processing themetal-cast article includes five steps consisting of steps ST11, ST12,ST13, ST14 and ST16. Note that the step ST12 (correcting step) is anessential step in the method for processing a metal-cast articleaccording to this exemplary embodiment, and therefore it is illustratedby solid lines. The other steps are illustrated by broken lines.

Firstly, as shown in FIG. 1, a metal-cast article is cast (step ST11).In the case of aluminum die casting, the temperature of the molten metalis, for example, about 680° C.

Next, in a cooling process for the metal-cast article taken out from thecasting apparatus, the metal-cast article starts to be pressurized by apress machine when the metal-cast article is at a somewhat hightemperature (specifically, before the temperature of the metal-castarticle decreases to 200° C. or lower) (step ST12). Note that if thetemperature of the metal-cast article is lower than 200° C. when thepressurization is started, distortion cannot be accurately removed. Inthe correction, the higher the temperature of the metal-cast article is,the more accurately distortion can be removed. Further, the higher thetemperature is, the more the necessary load for the correction can bereduced. Therefore, in the case of aluminum die casting, thepressurization is preferably started before the temperature of themetal-cast article decreases to 300° C. or lower. More preferably, thepressurization is started before the temperature decreases to 400° C. orlower. The temperature of the metal-cast article is, for example, about500° C. when it is taken out from the casting apparatus.

Further, the metal-cast article is preferably cast while measuring thetemperature of the metal-cast article so that cast metal-cast articlesare cast under the same temperature condition as each other.

The press machine includes cooling means and cools the metal-castarticle to, for example, 100° C. or lower while maintaining thepressurized state of the metal-cast article by the press machine.Details of the press machine are described later.

Next, an unnecessary part(s) of the metal-cast article taken out fromthe press machine is trimmed off by, for example, a shearing machine(step ST13). Note that examples of the unnecessary part include anoverflow part caused by die casting and a casting plan part such as abiscuit/runner part. The lower the temperature, the higher the accuracyof the trimming becomes. Therefore, as described above, the trimming ofthe unnecessary part of the metal-cast article is preferably performedafter the metal-cast article is cooled to 100° C. or lower by the pressmachine.

After that, a solution treatment is performed (step ST14). The solutiontreatment is a process for bringing alloy elements into a solid solutionstate in a matrix by rapidly cooling the metal-cast article afterkeeping the metal-cast article at a relatively high temperature for apredetermined time. In the case of aluminum die casting, the temperatureof the solution treatment is, for example, about 500° C.

After that, an aging process is performed (step ST16). The aging processis a process for strengthening the alloy by keeping the metal-castarticle at a temperature between a normal temperature and the solutiontreatment temperature for a predetermined time and thereby precipitatingthe solid-solution elements. In the case of aluminum die casting, theaging temperature is, for example, about 220 to 230° C.

Here, a method for processing a metal-cast article according to acomparative example is explained with reference to FIG. 2. FIG. 2 is aflowchart showing a method for processing a metal-cast article accordingto the comparative example.

Casting (step ST1), trimming (step ST3), a solution treatment (stepST4), and an aging process (step ST6) shown in FIG. 2 are similar to theabove-described casting (step ST11), the trimming (step ST13), thesolution treatment (step ST14), and the aging process (step ST16),respectively, shown in FIG. 1. Therefore, their detailed explanationsare omitted.

In the comparative example, a metal-cast article taken out from acasting apparatus is put into a water tank and thereby water-cooled(step ST2), and an unnecessary part(s) of the metal-cast article takenout from the water tank is trimmed off (step ST3). Then, the metal-castarticle is heated again and a press-correction is performed for themetal-cast article by a press machine after the solution treatment (stepST4) and before the aging process (step ST6).

FIG. 3 is a schematic temperature chart showing a comparison between themethod for processing a metal-cast article according to the firstexemplary embodiment and that according to the comparative example. Asshown in the upper part of FIG. 3, in the correcting step for ametal-cast article according to the comparative example, it is necessaryto heat the metal-cast article again just for the correction after themetal-cast article is rapidly cooled in the solution treatment. Further,the corrected metal-cast article is heated again for the aging processafter being cooled.

In contrast to this, as shown in the lower part of FIG. 3, in thecorrecting step in the method for processing a metal-cast articleaccording to this exemplary embodiment, the metal-cast article taken outfrom the casting apparatus is corrected when the metal-cast article isat a somewhat high temperature (specifically, before the temperature ofthe metal-cast article decreases to 200° C. or lower) in the coolingprocess of the metal-cast article. In the example shown in the figure,the metal-cast article is corrected when its temperature is about 500°C. Since the metal-cast article is corrected when the metal-cast articleis at a somewhat high temperature as described above, distortion can beaccurately removed. Further, since the metal-cast article is correctedin the cooling process of the metal-cast article, which is performedduring the casting process, there is no need to heat the metal-castarticle for the correction. As a result, the overall energy efficiencyof the method for processing the metal-cast article is excellent. Inaddition, since the processing time can be reduced by an amount roughlyequivalent to the time required for the correction in the comparativeexample, the productivity of the method for processing the metal-castarticle as a whole is excellent.

Further, in the correcting step for the metal-cast article according tothe comparative example, it is necessary to set the heating temperatureto a temperature lower than the aging temperature. In the case ofaluminum die casting, since the aging temperature is about 220 to 230°C., the heating temperature for the correction is, for example, about200° C. In contrast to this, since the correcting step for themetal-cast article according to this exemplary embodiment is performedbefore the solution treatment, the temperature of the metal-cast articlein the correcting step is not restricted by the aging temperature. Thatis, the temperature of the metal-cast article in the correcting step canbe raised to a temperature higher than the aging temperature. Therefore,compared to the comparative example, distortion can be removed moreaccurately and the load required for the correction can be reduced.

Further, in view of the manufacturing equipment, the use of the methodfor processing a metal-cast article according to this exemplaryembodiment can eliminate the need for the water tank for thewater-cooling, which is necessary in the comparative example, thusmaking it possible to reduce the necessary space for the manufacturingequipment.

Next, a configuration and an operation of a correction apparatus for ametal-cast article according to this exemplary embodiment are explainedwith reference to FIGS. 4 and 5. FIGS. 4 and 5 are schematic crosssections showing a correction apparatus for a metal-cast articleaccording to the first exemplary embodiment. FIG. 4 shows a state in thecorrection apparatus before a metal-cast article 40 is pressurized. FIG.5 shows a state in the correction apparatus where the metal-cast article40 is being pressurized. Note that the right-handed xyz-coordinatesystems shown in FIGS. 4 and 5 and other figures, which are consistentwith each other in these figures, are shown just for the sake ofconvenience for explaining the positional relation among components.Typically, the xy-plane forms a horizontal plane and the positivedirection on the z-axis is the vertically upward direction.

Firstly, the configuration of the correction apparatus for a metal-castarticle according to this exemplary embodiment is explained withreference to FIGS. 4 and 5. The correction apparatus according to thefirst exemplary embodiment is a press machine including an upper mold 10and a lower mold 20 that are disposed to be opposed to each other. Forexample, the upper mold 10 is a movable mold and the lower mold 20 is afixed mold. Projections and depressions corresponding to the shape ofthe metal-cast article 40 are formed on the opposed surfaces of theupper and lower molds 10 and 20. The upper mold 10 can be verticallymoved by a servo-motor (not shown) through a piston rod 11. As the uppermold 10 is lowered, the metal-cast article 40 is pressurized and therebycorrected by the upper and lower molds 10 and 20. The piston rod 11 isequipped with a load cell 12 for measuring the load applied on themetal-cast article 40. The load cell 12 makes it possible to apply anoptimal load to the metal-cast article 40 for achieving predetermineddimensional accuracy.

In the correction apparatus for a metal-cast article according to thisexemplary embodiment, coolant channels (refrigerant channels) WC areformed inside of each of the upper and lower molds 10 and 20. In thisway, as shown in FIG. 5, the metal-cast article 40 can be efficientlycooled in the state where the metal-cast article 40 is pressurized. Inthe example shown in the figures, a plurality of coolant channels WCeach having a U-shape in cross section are formed in each of the upperand lower molds 10 and 20. As described above, the correction apparatushas a configuration in which a plurality of coolant channels WCs areseparately provided in each of the upper and lower molds 10 and 20 andthe amounts of the coolants for these coolant channels WC can beindependently controlled.

Further, as shown in FIG. 4, a temperature in an area near themetal-cast article 40 inside of each of the upper and lower molds 10 and20 can be measured by a thermocouple TC. That is, the temperature of themetal-cast article 40 can be indirectly measured. Therefore, it ispossible to uniformly cool the whole metal-cast article 40 by adjustingthe amount of the coolant for each of the coolant channels WC in each ofthe upper and lower molds 10 and 20 while measuring the temperature ofthe metal-cast article 40. Further, since the correction can be startedat the same temperature for every metal-cast article 40 by measuring thetemperature of the metal-cast article 40 by the thermocouple TC,variations among products can be reduced. Note that arrangement examplesof the coolant channels WC are described later.

Next, the operation of the correction apparatus for a metal-cast articleaccording to this exemplary embodiment is explained with reference toFIGS. 4 and 5. When the temperature of the metal-cast article 40 placedin the correction apparatus reaches a predetermined temperature in thecooling process, the upper mold 10 is lowered as shown in FIG. 4. As aresult, the metal-cast article 40 is sandwiched between the upper andlower molds 10 and 20 and thereby corrected as shown in FIG. 5. As shownin the temperature chart in the lower part of FIG. 3, the metal-castarticle 40 is pressurized without making any coolant flow inside theupper and lower molds 10 and 20 for a predetermined period after thepressurization is started. That is, while maintaining the metal-castarticle 40 at a high temperature, the load on the metal-cast article 40is continuously or repeatedly measured by the load cell 12 so that themetal-cast article 40 is corrected by a predetermined optimal load.

After that, as shown in FIG. 5, the metal-cast article 40 is cooled bymaking coolants flow through the coolant channels WC formed inside theupper and lower molds 10 and 20 while maintaining the metal-cast article40 in the pressurized state. As described above, the amount of thecoolant for each of the coolant channels WC in each of the upper andlower molds 10 and 20 is adjusted while measuring the temperature of themetal-cast article 40 by the thermocouple TC. In this way, the wholemetal-cast article 40 is uniformly cooled and hence thermal distortioncan be prevented or reduced.

Through the above-described operation of the correction apparatus, apress-correction can be performed for the metal-cast article 40 takenout from the casting apparatus, whose temperature has reached thepredetermined temperature, in the cooling process of the metal-castarticle 40.

Next, a method for controlling the cooling temperature for themetal-cast article 40 is explained with reference to FIGS. 6 and 7. FIG.6 shows a plan view showing an arrangement example of coolant channelsWC and thermocouples TC in the upper mold 10, and cross sections takenalong respective cutting lines in the plan view. FIG. 7 is a flowchartshowing a method for controlling a cooling temperature for a metal-castarticle. Note that in the plan view in FIG. 6, the thermocouples TC areindicated by hatching so that the coolant channels WC and thethermocouples TC can be easily distinguished from each other.

Firstly, an arrangement example of coolant channels WC and thermocouplesTC in the upper mold 10 is explained with reference to FIG. 6.

As shown in the plan view in FIG. 6, five mutually-independent pairs ofcoolant channels WC, i.e., ten coolant channels WC in total are formedin the upper mold 10. As shown in the lowermost cross section and thesecond cross section from the bottom in FIG. 6, each of the coolantchannels WC is formed in a U-shape in cross section so that a coolantflows into the coolant channel WC from the top surface of the upper mold10, passes through an area near the bottom surface of the upper mold 10,and flows out from the coolant channel WC from the top surface of theupper mold 10.

As shown in the plan view in FIG. 6, two coolant channels WC each havinga U-shape in cross section as described above are disposed to be opposedto each other with one thermocouple TC disposed therebetween. Further,in total, five sets each of which consists of two coolant channels WCand one thermocouple TC as described above are arranged in the fourcorners and the center of the upper mold 10. Since the center of themetal-cast article 40 is less likely to be cooled, the two coolantchannels WC disposed at the center of the upper mold 10 are thicker(i.e., larger in diameter) than the other eight coolant channels. Withthe above-described configuration, the whole metal-cast article 40 canbe uniformly cooled.

As shown in the uppermost cross section and the second cross sectionfrom the top in FIG. 6, each of the thermocouples TC is inserted fromthe top surface of the upper mold 10 to an area near the bottom surfacethereof in order to measure the temperature of the metal-cast article40. By continuously or repeatedly measuring the temperature of themetal-cast article 40 by each of the thermocouples TC, it is possible toadjust the flow rates of the coolants made to flow through the twocoolant channels WC disposed on the periphery of that thermocouple TCaccording to the measured temperature of the metal-cast article 40. Asdescribed above, the flow rates for the five pairs of coolant channelsWC corresponding to the five thermocouples TC can be adjustedindependently of each other. With the above-described configuration, thecooling temperature in each part of the metal-cast article 40 can becontrolled. As a result, the whole metal-cast article 40 can beuniformly cooled.

Note that the coolant channels WC and the thermocouples TC in the lowermold 20 are similar to those in the upper mold 10, and therefore theirexplanations are omitted. Further, needless to say, the arrangementexample of the coolant channels WC and the thermocouples TC shown inFIG. 6 is merely an example. That is, the arrangement of coolantchannels WC and thermocouples TC is not limited to the above-describedarrangement.

Next, a method for controlling the cooling temperature for themetal-cast article 40 is explained with reference to FIG. 7.

As shown in FIG. 7, upon starting to cool the metal-cast article 40 bystarting to make a coolant flow to the upper and lower molds 10 and 20,the temperature of the metal-cast article 40 at a time t is measured bythe thermocouple TC (step ST51). Note that the time t means a timeelapsed from the start of the cooling.

Next, it is determined whether or not the measured temperature of themetal-cast article 40 at the time t is within a target temperature range(step ST52). Note that the target temperature and its tolerance rangefor the metal-cast article 40 at the time t are determined in advance bypreliminary tests or the like. When the temperature of the metal-castarticle 40 is within the target temperature range (Yes at step ST52),the process returns to the step ST51 without changing the amount of thecoolant.

On the other hand, when the temperature of the metal-cast article 40 isnot within the target temperature range (No at step ST52), the processreturns to the step ST51 after changing the amount of the coolant (stepST53). Specifically, when the temperature of the metal-cast article 40is higher than the target temperature range, the amount of the coolantis increased, whereas when the temperature of the metal-cast article 40is lower than the target temperature range, the amount of the coolant isreduced. The above-described control is performed for each pair of twocoolant channels WC disposed on the periphery of its correspondingthermocouple TC. Consequently, the whole metal-cast article 40 can beuniformly cooled.

As explained above, in the method for processing a metal-cast articleaccording to this exemplary embodiment, the metal-cast article iscorrected before the temperature of the metal-cast article decreases to200° C. or lower after the casting is finished. Since the metal-castarticle is corrected in the cooling process of the metal-cast articlefor the casting process, there is no need to heat the metal-cast articlefor the correction. As a result, the overall energy efficiency andproductivity of the method for processing the metal-cast article isexcellent. Further, since the metal-cast article is corrected before thetemperature of the metal-cast article decreases to 200° C. or lower,distortion can be accurately removed. That is, the method for processinga metal-cast article according to this exemplary embodiment makes itpossible to accurately remove distortion and has excellent productivityand energy efficiency.

Second Exemplary Embodiment

Next, a method for processing a metal-cast article according to a secondexemplary embodiment of the present invention is explained withreference to FIG. 8. FIG. 8 is a flowchart showing a method forprocessing a metal-cast article according to the second exemplaryembodiment.

In the first exemplary embodiment, as shown in FIG. 1, after thepress-correction is performed for the metal-cast article taken out fromthe casting apparatus, whose temperature has reached the predeterminedtemperature, by using the press machine in the cooling process of themetal-cast (step ST12), an unnecessary part(s) of the metal-cast articletaken out form the casting apparatus is trimmed off by, for example, ashearing machine (step ST13). In contrast to this, in the secondexemplary embodiment, as shown in FIG. 8, after the press-correction isperformed for the metal-cast article taken out from the castingapparatus, whose temperature has reached the predetermined temperature,by using the press machine in the cooling process of the metal-cast, themetal-cast article is cooled while maintaining the pressurized state ofthe metal-cast article by the press machine and an unnecessary part(s)of the metal-cast article that sticks out from the press machine istrimmed off by a shearing machine (step ST22). This step ST22corresponds to a method for processing a metal-cast article according tothis exemplary embodiment and includes a correcting step and a trimmingprocess for the metal-cast article. The other configuration is similarto that of the first exemplary embodiment and therefore its explanationis omitted.

FIG. 9 is a schematic temperature chart showing a comparison between themethod for processing a metal-cast article according to the firstexemplary embodiment and that according to the second exemplaryembodiment. As shown in the upper part of FIG. 9, the processing methodaccording to the first exemplary embodiment requires a time becauseafter the metal-cast article is taken out from the press machine for thecorrection, the metal-cast article is moved to a shearing machine or thelike to perform trimming for the metal-cast article.

In contrast to this, as shown in the lower part of FIG. 9, in the methodfor processing a metal-cast article according to this exemplaryembodiment, the metal-cast article is cooled while maintaining thepressurized state of the metal-cast article by the press machine and anunnecessary part(s) of the metal-cast article that sticks out from thepress machine is trimmed off by a shearing machine. That is, thecorrection apparatus for a metal-cast article according to thisexemplary embodiment includes a shearing machine as well as the pressmachine and hence can perform trimming as well as the correction.Details of the correction apparatus according to this exemplaryembodiment are described later. Therefore, this exemplary embodiment canreduce the time required for the trimming in the first exemplaryembodiment and hence improve the overall productivity of the method forprocessing the metal-cast article even further. Further, in view of themanufacturing equipment, the use of the method for processing ametal-cast article according to this exemplary embodiment can eliminatethe need for the separate shearing machine, which is necessary in thefirst exemplary embodiment, thus making it possible to reduce thenecessary space for the manufacturing equipment.

Next, a configuration and an operation of a correction apparatus for ametal-cast article according to this exemplary embodiment are explainedwith reference to FIGS. 10 to 12. FIGS. 10 to 12 are schematic crosssections showing a correction apparatus for a metal-cast articleaccording to the second exemplary embodiment. FIG. 10 shows a state inthe correction apparatus before a metal-cast article 40 is pressurized.FIG. 11 shows a state in the correction apparatus where the metal-castarticle 40 is being pressurized. FIG. 12 shows a state in the correctionapparatus where unnecessary parts such as an overflow part 40 a and abiscuit/runner part 40 b are sheared off.

Firstly, the configuration of the correction apparatus for a metal-castarticle according to this exemplary embodiment is explained withreference to FIGS. 10 to 12. The correction apparatus according to thesecond exemplary embodiment includes a shearing mold 30 in addition tothe press machine including the upper mold 10 and the lower mold 20 thatare disposed to be opposed to each other. In the second exemplaryembodiment, in addition to the upper mold 10, which can be verticallymoved, the lower mold 20 can also be vertically moved by a servo-motor(not shown) through a piston rod 21.

When the metal-cast article 40 is corrected, the upper mold 10 islowered so that the metal-cast article 40 is pressurized and therebycorrected by the upper and lower molds 10 and 20. Further, when shearingis performed, the upper and lower molds 10 and 20 are lowered in asynchronized manner while maintaining the pressurized state of themetal-cast article 40 by the upper and lower molds 10 and 20. In thisway, unnecessary parts (the overflow part 40 a and the biscuit/runnerpart 40 b) of the metal-cast article 40, which stick out from the upperand lower molds 10 and 20, are trimmed off by the fixed shearing mold30.

Alternatively, the correction apparatus may be configured so that,instead of lowering the upper and lower molds 10 and 20, the shearingmold 30 is lifted to shear off unnecessary parts (the overflow part 40 aand the biscuit/runner part 40 b).

Next, the operation of the correction apparatus for a metal-cast articleaccording to this exemplary embodiment is explained with reference toFIGS. 10 to 12. When the temperature of the metal-cast article 40 placedin the correction apparatus reaches a predetermined temperature in thecooling process, the upper mold 10 is lowered as shown in FIG. 10. As aresult, the metal-cast article 40 is sandwiched between the upper andlower molds 10 and 20 and thereby corrected as shown in FIG. 11. Asshown in the temperature chart in the lower part of FIG. 9, themetal-cast article 40 is pressurized without making any coolant flowinside the upper and lower molds 10 and 20 for a predetermined periodafter the pressurization is started. That is, similarly to the firstexemplary embodiment, while maintaining the metal-cast article 40 at ahigh temperature, the load on the metal-cast article 40 is continuouslyor repeatedly measured by the load cell 12 so that the metal-castarticle 40 is corrected by a predetermined optimal load.

After that, as shown in FIG. 11, the metal-cast article 40 is cooled bymaking coolants flow through the coolant channels WC formed inside theupper and lower molds 10 and 20 while maintaining the metal-cast article40 in the pressurized state. Similarly to the first exemplaryembodiment, the amount of the coolant for each of the coolant channelsWC in each of the upper and lower molds 10 and 20 is adjusted whilemeasuring the temperature of the metal-cast article 40 by thethermocouple TC. In this way, the whole metal-cast article 40 isuniformly cooled and hence thermal distortion can be prevented orreduced.

Next, as shown in FIG. 12, the upper and lower molds 10 and 20 arelowered in a synchronized manner while maintaining the pressurized stateof the metal-cast article 40, and unnecessary parts (the overflow part40 a and the biscuit/runner part 40 b) of the metal-cast article 40 arethereby trimmed off by the fixed shearing mold 30.

Through the above-described operation of the correction apparatus, inthe cooling process of the metal-cast article 40 taken out from thecasting apparatus, after the press-correction is performed for themetal-cast article 40, whose temperature has reached the predeterminedtemperature, the metal-cast article 40 is further cooled and unnecessaryparts can be trimmed off.

Note that the present invention is not limited to the above-describedfirst exemplary embodiment, and it can be modified as appropriatewithout departing from the sprit and scope of the present invention.

For example, the target metal-cast articles are not limited to thedie-cast articles. That is, they may be metal-cast articles formed bygravity casting, low-pressure casting, or other casting methods.

Further, the type of molten metal is not limited to aluminum. That is,the molten metal may be magnesium, iron, other metals, or alloys.

Further, the refrigerant is not limited to coolants and other types ofrefrigerants may be used.

The cooling means for a metal-cast article may have a configuration inwhich air or other cooling gases are blown on the metal-cast article.

From the invention thus described, it will be obvious that theembodiments of the invention may be varied in many ways. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention, and all such modifications as would be obvious to one skilledin the art are intended for inclusion within the scope of the followingclaims.

What is claimed is:
 1. A method for processing a metal-cast articlecomprising a correcting step of starting to pressurize the metal-castarticle by a press machine before a temperature of the metal-castarticle decreases to 200° C. or lower after casting is finished.
 2. Themethod for processing a metal-cast article according to claim 1, furthercomprising a trimming step of cooling the metal-cast article to a normaltemperature while maintaining the pressurized state of the metal-castarticle by the press machine, and shearing off an unnecessary part ofthe metal-cast article.
 3. The method for processing a metal-castarticle according to claim 2, wherein the press machine comprises anupper mold and a lower mold with a refrigerant channel formed therein,and when the metal-cast article is cooled, a refrigerant is made to flowthrough the refrigerant channel.
 4. The method for processing ametal-cast article according to claim 3, wherein when the metal-castarticle is cooled, the temperature of the metal-cast article ismeasured, and a flow rate of the refrigerant is adjusted based on themeasured temperature.